Centering means for boring machines



w. F. MITCHELL CENTERING MEANS FOR BORING MACHINES Dec. 18, 1945.

Original Filed March 18, 1943 Z She etS-Sheet 1 1 1N VEN TOR. waZZacca F/YLZZ/zeZ Dec. 18, 1945.

Original Filed March 18, 1943 2 Sheets-Sheet 2 MN M K N f. x MN Q .I MNw Q Q H HHU a kN W JJ MAN/ U W IN V EN TOR.

Patented Dec. 18, 1945 I I ase nsa etNrEi maMhANs tno t uemac Wallace F; Mitchell, Chicago, 111., assignor: to Automotive Maintenance Machinery- Goi; North 'flhica oil la, a. orp r ion. of; I lin is,

Qt i aiamlicatieh h. 124a Seria No.-

479,579.." Divided; and this application February 17-, 1944, Serial No. 522,:165

. I Z;Q ?2i. M r-inv on r lates gen ra y b r g. ie.-

hi s d p for e. boring, 'Qi' ne or a plurality i e ed iii e earings: and. t ha o d p ticu arl i hme ns in: ente ing. a bor a el t t th be rin t beb ed Th apb ie en e. di si n. of; y o endins application'Serial No. 419.5.7an1 18, 1943,, for Boring machine. i li et f in he. se. o ma hines for boring r g i ha be n. necessar o u re d c n ri g r g to. pro erl ce te he, b ri g b r the beari g to be ored This. rior operati n uir is seem y and as m f the bearings in the cen ring opcration, In the useof c nt in ring gr at, numb r f difie ent size ngsa elhe es ery order o ta e care of di fe ent size ea n s and, a will, be ap e ated, t i ihipieet ea tQ-ha e ava ab e a all time th r ng of, pr be: size. o. f ect. r er centering ope ations. here ore a iebis 'lt o h present invention is tq provideiniproved centering means for aligning the boring bar with the bearings; to b ed. the, rrang m be n u h a the bor ng bar ma be. een er l insb to a d ra ge ct. bear n s zes. w heut, dismant i the rin s o re o in the o ine bare Ano he b ec s. t r vi e a centering de o the foregoin cha act r wh ch i s m e n cone xti ct on, ea y to ope ate, and may be. manuf e-. tured at a low cost, and which is so. constructed nd. ar a ed ha the bor g bar may e itively, accurately and rapidlycentered with, re-. spect tobearings to'be bored.

' A further object is, to provide, an arrangement for, boring hearings or an engine or the like withou distu ng be r h a s. nd i se s. th late ter remaining in normal assembled condition durhis th comp e, p r o A more specific object is to provide a centering fixture of the foregoing character which is adapt ed through a singlefadjustment to. center itself with n th bearing to be. bored and to also center the boring-bar within the fixture and with re-, shee osu h e i e- 1 1 Other objects and advantages will become. apparent ast i des r ti n p o ress d by re er nee to t dr wi g eie h' Figure 1 is a longitudinal sectional view of a line boring tool including a boring bar having centering means embodying my invention applied In Fig. 1 oi the drawings there is illustrated in part, a line boringrnachine whichis shown and des rib d. u ete iin, y a nd ng epieet en eria v Q- 79 T hin e des a bo h r ic is rete eb y ubber ed by a u ali o pae si e t n II carried b un v rsa y m u e a n up o I2. e in ban. n. use i en e h. espect. to a plnrality, of bearings I3 which 'are to be bored and when sccentered the supports {2 are locked in that condition as more particularly exblam d n my, s d. ope he p ca on- The present application has to do particularly wi h a xtu l 4 h h I e pl y or nt rin t b r n b r 0. in h e i s, i x u e is adapted or ea nd ck y centering th borin bar with a minimum of manipulation of par he. b a i nee n t. be. d ur d for this purpose. and asinglg fixture will serve for centerin the bor n bar in Wi e ran bearing sizes. It is to be understood that although my invention is particularly suited for the Work just theretq br centering the boring bar with respect tov t e h a i gs t be b ed:

Fig. 2 is an enlargedseparated assembly view of the centering fixture. shown in Fig. 1;

Fig. 3 is an enlarged end view taken substantially on line 33 of Fig. 1;, I

Fig, 4 is a vertical sectional view taken substantially on line 41-4 of Fig. 3; and Fig. 5 a transverse. sectional view. takensubstantially on line 5,- 5, cf Fig e.

stated. it, can be used and has utility in connectionwith the boring of bearings of any kind where similar conditions of use are to be met and wherever the mechanism is capable of installation for utilization of the advantages to be attaincd through it.

More particularly. the centering fixture takes the form of a tubular body l5v having an enlarged head 16 and a reduced threaded shank l7, the

shank being slotted at l8 to provide a plurality (preferably three) of spaced compressible segments. 'Ijhe inner ends ofthe shank slots [8 terminate. in the head IS in such a way as to provide thereat tapered shoe-supporting surfaces [6 which serve as camways for supporting the inward ends of a plurality (preferably three) of expansible jaws or shoes l9. The jaws 19 are identical and each is provided with an outer elongated rounded face w and an inner face tapered at its opposite ends as at 20, and 2|. The surface 2!! is tapered. ccmplementally to the camway seats {6 formed in the body head and the other surface 2| is tapered complementally to the conical seat. 22 of an expanding centering cone 22 which isfreely slidable over the shank; H to the position indicated in Fig. 4 where, together with the seat Hi. of the body, it, supports the jaws 19 for expanding and contracting movement. The jaws were seated and maintained against the seats [6. and 22% by an external garter type spring 23 seated in grooves 2 4 in the outer central; portions of the jaws, IS. The expanding cone 22 is maintained in its jaw-supporting condition by a sleeve 25 which threadedlyengages the threaded shank- I 'I. oi the body [5. The forward edge 25 of the s e 25 bu e the ear e e 2- oi e cone. to hold it in position. It will be seen that the sleeve or collar 25 may be turned clockwise to move the cone 22 toward the body head l6 and tothereby expand the jaws l9 and it may be moved in the opposite direction to contract such jaws cooperatively with the spring 23.

When it is desired to bore the crank shaft hearing, such as illustrated at [3 in Fig. 1, the

centering fixture is applied to the end bearings expanding, take care of lateral or horizontal alignment. These upper jaws, together with the lowermost jaw, also take care of vertical alignment so that when the jaws are all engaged with the bearing the fixture itself is centeredin the bearing. To accomplish this the jawsare located at spaced intervals of approximately 120.

After the jaws [9 are firmly engaged with the r bearing l3, the sleeve or collar 25 may be further tightened and in doing so the flexible segments of the body shank I! are uniformly contracted into tight gripping engagement with the boring bar l0. of the threads of the collar to grip or slip over the threads of the shank I'I., In other words, I rely upon the camming action of the threads after the jaws are tightly set up, preventing normal turning of the sleeve in clockwise direction to effect a clamping action around the bar. This is a collet-like action wherein the different segments of the shank I1 contract uniformly and in doing this they in turn center the boring bar within the bearing centered fixture. This centering fixture eliminates the necessity of using centering rings as heretofore. In the use of centering rings they had necessarily to fit freely so as to readily slide along the boring bar and in doing so presented an error in the centering action. In the present arrangement that error is avoided by firmly clamping the bearing in a tight-fitting centered condition which would be impractical in the use of centering rings. This fixture also lends itself to proper centering with- P out removal of the bearing caps or without disturbing the bearing in any manner after the boring bar centering and aligning operation has been performed. In the use of centering rings the bearing had to be dismantled both before and after the centering operation and this, as hereinabove pointed out, also tended to create error, particularly in th disassembly and assembly of the bearin after the use of the centering rings in the centering of the bearings. I prefer to effect the centering operation Within or from the bearing l3 itself but, if desired, the centering may be accomplished from the motor block. In other words, one can center either after the bearing has been inserted or before the bearing is inserted, preferably, though, after the bearing has been inserted.

In setting up the machine to bore the bearings l3 (Fig. 1), I first insert the boring bar I!) in the respectiv bridge bearings l l and also through the centerin fixtures, which are, at that time, in place in the respective end bearings. When I have done that I then center the boring bar It] in the end bearingsl3 as hereinabove explained. After having centered the boring bar It! in the end bearings, the bearing supports 1'2. are secured,

This action takes place due to the tendency thus securing the boring bar and its hearings in proper centered condition with respect to the bearings to be bored. After the boring bar I0 is thus fixed in its centered condition, the centering fixture is than removed. To this end the centering fixtures are merely released sufficiently to permit them to move readily in the respective bearings and upon the boring bar. The boring bar is then manually moved longitudinally, first one end and then the other, to an extent suf ficient to permit the removal of the centering fixtur from the end thereof, the boring bar being removed from any bearing supports that may be disposed outwardly beyond the bearings in which the centering fixtures are located. In each instance, while the boring bar is removed from its endmost bearing supports, it is supported by the remaining bearing so that no disalignment occurs because of this operation. After the centering fixtures have been removed and the boring bar is restored to its fully supported, aligned position, the machine is then ready to be driven for the boring operation. r

I believe that the advantages of my invention will be obvious from the foregoing description. The tool may be centered easily and quickly for the boring operation. The boring operation may be carried out with a higher degree of accuracy than heretofore. This is accomplished by the facile and accurate manner of centering the boring bar and the reduced number of manipulations required to accommodate th tool to the boring operation. This is also aided by the fact that my invention eliminates the necessity of centering rings or the like, thereby avoiding assembly and disassembly of the boring bar therein.

I claim:

1. In a machine for boring th bearings of an engine cylinder block, a boring bar, means for centering said boring bar in the bearings to be bored which includes a, cylindrical body member adapted to receive said boring bar and having a part compressible upon the boring bar, expansible centering members carried by said body member and adapted to engage the wall of a bearin to be bored, and means for expanding said expansible members including a member carried by said compressible body part for first expanding said expansible members and then compressing said compressible part when said expansible members are no longer expansible because of engagement with a bearing.

2. In a machine for boring the bearings of an engine cylinder block, a borin bar, means for centering said boring bar in the bearings to be bored which includes a cylindrical body member adapted to receive said boring bar and having a part compressible upon the boring bar, expansibl centering members carried by said body member and adapted to engage the wall of a bearing to be bored, and a single means adjustable to first expand said expansible elements and to then compress said compressible part.

3. In a machine for boring the bearings of an engine cylinder block, a boring bar, and means for centering said boring bar with respect to the bearings to be bored which includes a cylindrical body adapted to fit uponsaid boring bar, said body having a segmental shank portion externally threaded, a plurality of circumferem tially spaced jaw members carried by said body and adapted to be expanded to engage the wall thereon to expand said jaws, said member being adapted to compress the segments of said body shank into firm engagement with said boring bar when further expansion of said laws is prevented by their engagement with the bearing.

4. In a machine for boring the bearings of an engine cylinder block, aboring bar, and means for centering said boring bar with respect to the hearings to be bored which includes a cylindrical body having a shank portion exteriorly threaded and slotted longitudinally to provide a plurality of compressible segments, expansible jaws slidably mounted between said segments and having facesadapted to engage the wall of a bearing tobe bored, means for expanding said jaws including -a member mounted upon said threaded shank and adjustable longitudinally thereof, said member being adapted when expansion of said jaws is stopped by engagement with a bearing to compress said segments into firm engagement with said boring bar.

5. In a machine for boring the bearings of an engine cylinder block, a boring bar, and means for centering said boring bar with respect to the bearings to be bored, which includes a cylindrical body adapted to freel receive said boring bar and having a head with a reduced shank portion exteriorly threaded and having longitudinal slots at a plurality of points to provide a plurality of compressible segments, said head having tapered seats therein at the ends of and aligned with the slots in said shank portion, a sleeve member having an annular tapered seat atone end thereof slidably mounted on said shank portion, expansible jaw members mounted in said slots and having seat surfaces shaped complementally to and engaging said head and sleeve seats, the outer faces of said jaws being adapted to engage the wall of a hearing to be bored, and an internally threaded member mounted on said threaded shank and engaging said sleeve so that adjustment of said member in one direction moves said sleeve to expand said jaws, the threads of said member operating with the threads of said-shank to compress said segments toward said boring bar when further expansion of said jaws is prevented by their engagement with a bearing.

ing wall to center said body within the bearing,

and single means carried by said body member ing elements, and means carried by said body -member and shiftable axially therealong for moving said expanding part to expand said centering elements finally to cam said compressible segments inwardly so as to engage and center said body upon a boring bar when the expanding limit of said centering elements has been reached.

8. A centering fixture which comprises a cylindrical body member including a threaded shank portion slitted to provide equally spaced compressible segments, a plurality of centering elements mounted for expansion and contraction movements between said segments, means including an expanding element carried by said threaded shank for expanding and contracting said centering elements, and a member threadedly engaging said threaded shank portion and adjustable axially of said body member for moving said expanding element to expand and contract said centering elements and to force said compressible segments inwardly when expanding movement of said centering elements is stopped by engagement of the latter with a bearing surface or the like.

9. In a machine for boring alined bearings in a work piece, a boring bar, and means for centering said bar in said bearings, which includes a body member adapted to receive said bar and having a part compressible upon said bar, expansible centeringmeans carried by said body member and adapted to engage the wall of a bearing to be bored, and a single member adjust-' able to first expand said expansible means and then to compress said compressible part.

10. In a machine for boring alined hearings in a work piece, a boring bar, and means for centering said bar in said bearings, which includes a threaded body member adapted to receive said bar and having a part compressible upon said bar, expansiblecentering means carried by said body member and adapted to engage the wall of a bearing to be bored, and a member threaded on said body member and adapted when turned in one direction first to expand said expansible means and by continued turning in said direction to compress said compressible part.

11. A fixture for centering a boring bar in a a bearing, comprising: a threaded body member adapted to receive said bar and having a part compressible upon said bar, expansible centering means carried by said body member and adapted to be expanded into engagement with the wall of a bearing, and a member threaded on said body member and adapted when turned in one direction first to expand said expansible means into engagement with the bearing wall and, by continued turning in said direction, to compress said and adjustable longitudinally thereof to first compressible segments adapted to receive a boring bar for the boring of a bearing or the like, a plurality of expansible, and contractible centering elements carried by said body member, means supporting said centering elements and including a part shiftable along the body member for expanding and contracting said centercompressible part into gripping engagement with the boring bar.

12. A fixture for centering a boring bar in a bearing, comprising: a body member having a 

